Keeping in touch with your Martian pen pal won't be cheap according to the British postal service. Five-year old aspiring future astronaut Oliver Giddings of Lytham St Anne's in Lancashire asked the Royal Mail how much it would cost to post a letter to the Red Planet. After consulting with NASA's Kennedy Space Center in Florida, the answer came back: 18,416 First Class stamps costing £11,602.25 (US$18,003.40).

Sometimes an email just won't do the job, but sending a letter somewhere off the beaten path takes a bit of homework – especially to someplace like Mars, where the post office neglects to advertise the rates. The Royal Mail is a bit hazy on such out of this world destinations, hence the need to consult NASA for a few details to answer Oliver's question.

The £11,602.25 figure from the NASA Mars Outreach team is based on the distance of Earth to Mars using the Curiosity mission as an example and calculated for the upper weight of a standard letter.

"NASA also told me that their last visit to Mars, carrying the Curiosity rover, cost about $700 million US dollars," says Andrew Smout, Royal Mail senior customer advisor in his letter to Oliver. "The spaceship itself is very small, so storage is at a premium. Based on how much the spaceship weighed, compared to how much it costs to get to Mars; they said that something weighing up to 100 grams (3.5 oz) would cost them approximately $18,000 US dollars (£11,600) to fly to Mars."

The Royal Mail then tacked on £2.25 (US$3.40) to send the letter from Britain to a NASA launch site and the total came to £11,602.25.

Oliver's response: "Wow! That's a lot of money."

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